I'm working on a board with an ADAU1467 acting as an audio processor, and programmed with SigmaStudio 4.5. I'm currently stuck with a weird bug where I have several boards that will not program. As in, I'll run the link-compile-download sequence and the chip will not respond. Reading from the DSP registers gives me either a string of 0x00s or 0xFFs. I do not see any activity on the CLKOUT pin, even though I have a 12.288MHz crystal supplying a valid MCLK signal. Looking at the datasheet for the ADAU1467, it seems like the device is not booting up properly, perhaps the PLL is not locking and causing the control port to be held in reset (from page 26 of the datasheet).
I've probed the voltage rails and they all seem fine:
Here's a link to the DSP portion of my schematic, it's too big to fit into this post: https://i.imgur.com/hVk9kcg.png
What could be causing the chip to not boot up? Is there anything else I can probe or provide?
It's worth noting that 3 out of the 10 boards in this production batch seemed to work properly right away. I was able to salvage a few other boards by replacing the ADAU1467 with a fresh chip. A previous version of this board (with the exact same schematic and BOM) had 9 of the 10 boards program and boot properly.